Perform simplification of goal by conditional contextual rewriting using
assumptions.

DESCRIPTION

A call to PURE_ASM_SIMP_TAC[theorems] will apply conditional contextual
rewriting with theorems and the current assumptions of the goal to the goal's
conclusion, but not the default simplifications (see basic_rewrites and
basic_convs). For more details on this kind of rewriting, see SIMP_CONV. If
the extra generality of contextual conditional rewriting is not needed,
REWRITE_TAC is usually more efficient.